This invention relates to a stop motion device for a strand processing machine such as a textile spinning frame. While the specific disclosure of this application relates to a textile spinning frame, the invention has application to other types of strand processing machines, as well. In general, the invention provides a novel and unique apparatus and method of interrupting the supply of the strand to the processing station of the machine when the strand is no longer being fed to the take-up package.
Such an occurrence can create serious and even dangerous situation in the operation of the machine. In the case of a spinning frame, as disclosed below, a breakage of the spun yarn downstream of the drafting rollers can create a situation where the sliver being fed to the drafting rolls begins to "lap-up" around the drafting rolls. If this condition is not immediately detected, the sliver can wrap so tightly against and around the drafting rolls the removal becomes a time-consuming task. Yet, with the increasing use of high-speed automated machines fewer human attendants are used making prompt lap-up detection less likely.
Lap-ups create at least the problem of cutting the sliver away from the drafting rolls. This is done with very sharp knife which if not used properly can cut and damage the rubber covering of the top drafting roll. If the damage is slight, it may not be immediately noticed but can drastically increase the incidence of broken ends. More serious damage will usually be noticed, but of course requires replacement of the drafting rolls and removal and recovering of the damaged ones.
Extremely large lap-ups can damage the machine by wrenching the top rolls out of their mounts and warping and otherwise damaging the drafting roll components.
Machine attendants also occasionally cut themselves with the very sharp knifes required to remove the sliver from the drafting rolls.
If the sliver does not lap-up, it is sucked into a vacuum tube. This material is called "waste." The waste must be disposed of or added back with the raw fiber being produced.
Stop motion devices are known which attempt to regulate this problem. However, these devices are characterized by the use of solenoids which must travel relatively long distances, must hold a heavy force and must hold it for a long period of time. All of these prior art features are serious impediments to effective and efficient detection and prevention of lap-ups.
The present invention uses a very small solenoid which must move only a short distance and is not required to hold any weight during its activation mode. Momentary movement of the solenoid activates a mechanical system, for example a tearing blade, which separates the sliver and prevents wrapping of the sliver around the drafting rolls.